Planbaraph co



S. RUDBERG.

ROCK DRILLING APPARATUS.

PP 1 ION mm NOV. 6. I917.

1,319,968. Patented Oct; 28,1919.

Z06 n'l'ir' /)Zi Aliza?" 696' UNITED STATES PATENT onnion.

STEN RUDBERG, 0F STOCKI-IOLM, SWEDEN.

ROCK-DRILLING APPARATUS.

Specification of Letters Patent. Patented 0013. 2S, 1919.

Application filed November 6, 1917. Serial No. 200,535.

matically and the invention has for its purpose to increase the effectivity of such apparatus or, more distinctly explained, to

cause a material increase of the number of hammer blows, which are delivered per unit of time upon the drill, so that the rapidity of drilling, that is to say, the depth, to

which the drill penetrates into the rock per unit of time during the drilling operation is increased.

The rapidity, with which the drilling (the penetration of the drill into the rock) occurs, is of course dependent partly upon the strength of the piston blows and partly on the period of time between each blow and the next. The power of each blow may however not exceed a certain maximum, as the drill then may burst and further the number of blows, which a piston can exert per unitof time is highly limited on account of the fact, that a certaintime is required for the piston to perform its reciprocating movement.

By using the apparatus, which is the object of the present invention, the drilling can be performed with a rapidity, which is twice or many times greater, than. that of the drilling apparatus hitherto known.

The invention is substantially characterized by the fact, that the apparatus is provided with two or more pistons, serving as hammers, which are coaxially arranged and alternately deliver blows upon the drill respectively upon an intermediate part (striking block or pin,) abutting against the inner end of the drill.

In the preferred embodiment, the machine is provided with two pistons, the one of which has a tubular shape, while the other piston is movable in the bore of the tubular piston. An embodiment of the invention, adapted on a pneumatically driven rock drilling apparatus, is illustrated in the accompanying drawing.

a indicates the drill, b the drill chuck, 0

intermediate block (5.

' mediate block.

the intermediate block, abutting against the inner end of the drill and upon which the piston blows are delivered, and d the outer asing or the cylinder of the apparatus. In this latter there arenow arranged, according to the present invention, two pistons c and 7, which can deliver blows upon the The one 0 of these pistons is of a tubular cross-section, and thus has an annular working surface. The

other piston f fits exactly into the tubular' piston 6, so that the two pistons may move freely in the longitudinal direction relatively to each other. Each piston is provided with a head, engaging the inside of the cylinder (Z. These two heads are actuated by the driving fluid in such a way, that they deliver alternate blows upon the interh and 9 indicate the two cylindrical chambers, in which the piston heads are moving.

It may be easily understood, that by this device a drilling rapidity is effected, which 7 is twice as great, as that which is obtained,

when using the drilling apparatus hitherto known, which latter only are provided with a single piston, working against the intermediate block (the drilling tool,) provided the strength of the blows and the stroke speed is the same 1n both cases.

' The pressure air for the power strokes flows through the channel 70 firstly above 4 the piston f in the upper part of the cylinder g for this piston and causesthis latter to exert'blows against the intermediate block 0. When the head of the piston f has passed the upper mouth of a channel it extending between the cylinders h and g, the pressure.

. air, now expanded. to a certain degree, passes to the cylinder 72, and acts upon the upper side of the head of the piston e, so that this latter delivers blows upon the intermediate striking block or pin a. after having acted upon this piston e escapes through the outlet 0.

The pressure air for lifting the pistons (the return strokes) enters through the channel Z and flows firstly to the bottom of the cylinder 9, so that the piston f is moved upward (lifted). When this piston f during its movement upward has passed the upper mouth of a channel m, extending between the lower parts of the cylinders g and h, the air below the head of the piston f flows through said channel m to the chamber below the head of piston e, so that this The pressure air latter piston is lifted. When the head of piston c has passed the outlet 0 flows the air below the head of said piston out through said oiitlet. The supply of air to the channels 7c and Z is regulated by means of a valve device of usual construction in such a way, that the flow of air to it is interrupted and the flow of air to Z begins, when the piston f is in its lowest position, while when the piston has reached its upper position, the flow of air to Z is interrupted and the flow of air to 70 begins.

What I claim is:

1. A pneumatically operated drill including a casing, a drill arranged in the lower end of said casing, an outer piston, an inner piston, passing through the outer piston so that the two pistons when operating deliver blows on different points of the same surface, a head on each of said pistons, means for causing pressure air to act on opposite sides of the heads so as to move the pistons toward and from the tool, a cylinder chamber for each or" said piston heads, a transverse wall separating said two cylinder chambers, the stem of the inner piston being tightly guided in said transverse wall.

2. A pneumatically operated drill including a casing, a drill arranged in the lower end of said casing, an outer piston, an inner piston passing through the outer piston so that the two pistons when operating deliver blows on dilferent parts of the same surface, a head on each of said pistons, a cylinder chamber for each of said piston heads, means for causing a quantity of pressure air to first move the inner piston clownward and then move the outer piston downward and to escape finally into the atmosphere, and for causing another quantity of pressure air to first move the inner piston upward, then move the outer piston upward and to escape finally into the atmosphere, said two cylinder chambers being separated from each other through a transverse wall, through which the stem of the inner piston passes.

3. A pneumatically operated drill including a casing, a drill arranged in the lower end of said casing, an outer piston, an inner piston, passing through the outer piston so that the two pistons when operating deliver blows on different points of the same surface, a head on each of said pistons, an upper cylinder chamber for the head of the inner piston, and a lower cylinder chamber for the head of the outer piston, a pressure air inlet channel opening into the upper end of the upper cylinder chamber, a pressure air inlet channel opening into the lower end of said cylinder chamber, a communicating passage extending to the upper end of the lower cylinder chamber from a point lying at some distance below the point at which the first named channel opens into the upper end of the upper cylinder chamber, a second communicating passage extending from a point of the upper cylinder chamber lying some distance below the upper mouth of the first con'nnunicating passage to the space or" the lower chamber below the head of the outer piston, said two cylinder chambers being separated from each other so that they only communicate through said passages, an outlet from the lower cylinder chamber, which outlet in the lower position of the outer piston communicates with the space above said piston, while said outlet in the upper position of the outer piston communicates with the space below said piston.

In testimony whereof I afiix my signature in presence of two witnesses.

STEN RUDBERG.

lVitnesses Gus'rar ZAUSSON, MALTE Krnnnncnann.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

